In order to study the north-south asymmetry in the intensity variation, particulary of sidereal anisotropy, of high energy cosmic rays (-10^<12>eV) we have collaboration between Shinshu University, Nagoya University and University of Tasmania for the period 1991-1992. We have started two hemisphere observations at two stations ; one at Matsushiro in the northen hemisphere and the other at Liapootah, Australia since December 1991. Two stations are located at a conjugate position at a similar geographical latituide and longitude, at almost the same depth underground of 220m.w.e. at Matsshiro and 154m.w.e. at Liapootah, respectively. The identical muon telescopes are installed ; 25m^2 in area at Matsushiro, and 20m^2 in area at Liapootah, both of which of multi-directional type. The telescopes and the electronics systems at both stations have been connected with each laboratory for controlling and data sending, by means of personal-computer systems, via pulic telephone lines.Continuous ob
… Moreservations commenced in December 1991 at Liapootah (at Matsushiro the observation has been carried out since April 1984).The following preliminary results are obtained :1. Observed counting-rates are in good agreement with those expected for each directional telescope at Liapootah.2. The measured counts well follow the Poisson fluctuation as expected.3. Good correlations (With coefficient -0.4 for 2968 data points) have been found between the observed intensity variations for the vertical telescope and the variations of the barometric pressures measured at Hobart (-90 km in distance). The barometer coefficient is -0.03%/hp, which is in agreement with th theoretical values by taking into accounts the upper atmospheric temperature effect.4. Mothly average values show a remarkable semi-annual variation as likely to that at Matsushiro ; two maxima at summer and winter seasons. These also can be well explained in terms of the temperature effect.5. The intensity variations are harmonically analyzed in solar, sidereal and anti-sidereal time, respectively. Significant sidereal diurnal vector is obtained at Liapootah for the vertical telescope as ; 0.057*0.014%, 3.1*1.0hr SLT. The value may be compared with that at Matsushiro ; 0.030*0.027%, 2.5 hr LST. This indicates that significant north-south asymmetry may be found in sidereal variation as has been expected.6. Monthly diurnal vectors in each time coordinate has been examined. It is well established that month-to-month movement of sidereal vectors, for example, can be well explained in terms of annual movements of solar and anti-sidereal vectors and their synthesis.6.恒星時日変化は0.057±0.014%,3.1±1.0hrと得られた。この値は松代での同期間の0.030±0.027%〜2.5hrと比べて位相はほぼ同じで,振幅は約2倍で,有為な南北非対称的異方性の存在をあらためて確認している。7.更に,それぞれの時間軸における観測月変化を調べた。太陽時日変化は恒星時と反恒星時の年周変化で,反恒星時は恒星時と太陽時,また恒星時の月毎の変化は太陽時と反恒星時変化の年平均値の年周変化でよく説明される。これらは,いずれも観測の正常さを強く証拠ずける。今後の観測から(短くとも11年間),南北非対称恒星時異方性の定量的確定が期待される。 Less